The Martin 5-15 was introduced in 2002 as a size 5 (Terz) bodied acoustic in the 15 Series. The top was solid sapele or mahogany with D-1 size 5 bracing. Sides were sapele or mahogany.

The 5-16GT was made between 2003 and 2004

The 5-17 (1927-1943 Mfg.) was made between 1927 and 1943

MARTIN manufactured the 5-17T between 1927 and 1943

The Martin 5-18, first listed in the 1898 Martin catalog, was the smallest of Martin's regular guitars. The 5-18 was just 11.25 inches at the widest part of the body and had a scale-length of only 21.4 inches - but these were big sounding little guitars. The size 5 instruments were often thought of as Junior instruments for children - but they originated from 19th century European Terz guitars. These Terz guitars were designed to be tuned three semitones higher than standard pitch - although the 5-18 can be tuned to standard pitch it sounds better when tuned higher.

Martin 5-28 is a three quarter sized acoustic produced from 1901 to 1939 and again from 1968 to 1981. The 5-28 has also been available recently as a Martin Custom Shop model and also influenced the design of the 1999 Mini Martin - as played by Sting.